Specifications

Chapter 3 Hardware

ReadyBoard 800 Reference Manual 51

Table 3-21. Infrared Interface Pin/Signal Descriptions (J9)

Pin # Signal Description

1 VCC +5 Volts DC +/ 5%

2 IRTX IR Transmit Data

3 CIRRX IR Mode Select

4 IRRX IR Receive Data

5 GND Ground

Note: The shaded area denotes power or ground.

System Management Bus (SMBus, J25)

The I/O Hub (Southbridge) chip (82801DBM) contains both a host and slave SMBus port; but the host

cannot access the slave internally. The slave port allows an external master access to the I/O Hub

through connector (J25). The master contained in the I/O Hub (82801DBM) is used to communicate

with the SODIMM EPROM, Super I/O, Ethernet 1 and 2, and the clock generator. Table 3-22 lists the

device name and corresponding reserved binary addresses on the SMBus. Table 3-23 lists the SMBus

pin/signals on 5-pins, 1 row, 2 mm pin spacing on the external SMBus connector (J25). .

Table 3-22. SMBus Reserved Addresses

Component Address Binary

SODIMM EPROM 1010,000x

Clock Generator (ICS950201) 1101,001x

I/O Hub (82801DBM) 1000,100x

I/O Hub (82801DBM) 0001,000x

Note: The I/O Hub has two reserved addresses.

Table 3-23. SMBus Signals Pin/Signal Descriptions (J25)

Pin # Signal Description

1 VCC5Dual +5V standby voltage

2 SMBCLK SMBus Clock

3 SMBDATA SMBus Data

4 SMBALERT* SMBus Alert

5 GND Ground

Notes: The shaded area denotes power or ground. The signals marked with * = Negative true logic.

Real Time Clock (RTC)

The I/O Hub contains a Real Time Clock (RTC) and an external Lithium Battery (B1) provides power

for the RTC and the CMOS RAM through connector BT1. The CMOS RAM is backed up with a

Lithium Battery. If the battery is not present or defective, the BIOS has a battery-free boot option to

complete the boot process.